Since I changed from the egg shaped shaft zincs to the donut shape, they have stayed on much longer. The lack of meat around the screws on the egg shape caused them to fall off when only 10% gone (or so), while the other shape hangs in to 40% gone. I haven't seen the donuts any worse than 40% gone, and I have lost some before the next haulout, so I can only assume they don't hang in much past 40%.
I have seen several brush systems, but they all look pretty Mickey Mouse (no offence intended Minnie) and I have no desire to try one.

West marine sells them for about 40 bucks.* Have seen them on some of the newer boats.* I looked at them but decided to stay with the collar zincs on the shaft.* The reason is if there is not zinc protection then the zinc in the bronze prop will be used turning the prop pink and the you get to replace them.* Instead when at the dock I connect a Grouper zinc over the side instead.* The Groupers prolong the shaft zincs and are easy to check.* *However, the shaft brushes are very easy to install.* I would do both but not eliminated the shaft collar zinc, incase the shaft collar zoinc fails.

I just went back to the zinc nut thing. My last one disappeared and I assumed the screw backed off and the zinc fell off. I got rid of the flying saucer shaped zincs on my rudder thinking them a bad design and put a zinc w ears on the ends that were'nt zinc* (probably made for metal boats intended to be welded on) so the zinc would stay firmly in place bolted to the rudder as the zinc eroded. I had a boat w a brush on the shaft and didn't like what it did to the shaft but didn't get much time on the boat*** .. then I sold it. On another boat I intended to put a brush on it but never got around to it. I used a wire w a zinc on one end and a clip on the other. Put the clip on the shaft and the zinc end over the side in the water. Worked much better than I ever imagined*** .. was hardly any trouble and eliminated all the problems of the other alternatives. The clip didn't even slip off and allow the wire and all to zip right into the bay.
Eric Henning

We had shaft brushes installed on our boat right after acquiring it. So they've been there for almost eleven years and have had no effect on the shaft (stainless) at all other than keeping the surface of the shaft underneath the brushes shiny. There is no wear.

Our marina is pretty hot, so on the advice of our marine electric shop we have two egg-zincs on each shaft plus the shaft brushes plus the two transom zincs plus a zinc hung on a heavy wire down about eight feet when we're in our slip. This last is there because with a large river emptying into Bellingham Bay plus a pretty high-volume stream coming in right next to the marina, the surface water can be almost devoid of any trace of salt which means very little conductivity through the transom zincs. So a lot of marina residents hang a zinc on a wire that's clamped to something attached to the bonding system to put a zinc down into the salt water below the fresh or brackish surface water.

Even with the shaft brushes, the shaft zincs go away in about six or seven months (we have them changed by a diver) so I would not want to eliminate them as they are obviously an active part of the protection system.* But every boat and every marina will be different so the best thing is to get advice from a local electrical shop and then if they believe the shaft brushes will eliminate the need for shaft zincs, give it a try and monitor what's going on with your through hulls and other stuff that the bonding system is protecting.

Very good info for me Marin*** thank you. We get much more fresh water in our harbor than you so this is very applicable to all here. I'll set up a wire very soon and follow suit. Routing and deploying the wire ect will be more challengeing than the Albin was. Perhaps it's a good thing I now have a nibral prop. I think this is where I'll apply your anchor philosophy***** .. the more the better. Thanks again for the heads up on the stratification of sea water and fresh water. We do have a much elevated ice problem in Thorne Bay because of it. So far this year we have considerable ice but nothing like last year*** .. whole harbor froze in w 3" solid ice.

I was told not to skimp on the wire so I used a length of automotive battery cable. The boat end is fed down through a covered deck hawse into the lazarette and clamped to the port bronze rudder post, which is also tied into the boat's bonding system. The other end is "connected" to a used transom zinc with a stainless eye bolt, three nuts and two fender washers. The strands of the stripped battery cable are splayed out, and fork around the bolt and are mashed onto the zinc's center plate by one of the fender washers.

I tied a line to the eye of the bolt and let the zinc down to the depth I want. A loop in the boat end of the line goes around one of the aft cleats. So the weight hangs on the line, not the cable. Rather than take all this apart every time we take the boat out, I just pull up the line, wire, and zinc and set it in a bucket on the aft deck. Changing the zinc is just a matter of removing the two "end" nuts and fender washer, putting the bolt though the slot on a replacement zinc, and putting the nuts and fender washer back on to clamp the wire to the zinc again.

My wife made a big fabric "Stop-Zinc" sign that we hang on the shifters whenever we deploy the zinc, which is only in our home slip. This will (hopefully) prevent me or someone servicing the boat from starting the engines and putting the transmission in gear. Turning the port prop under power could conceivably pull the zinc or the line or cable into it.

An advantage of this arrangement is you now have a zinc in the bonding system that you can pull up and take a look at.* If the zinc goes away at its normal rate for your harbor, everything is working fine.* But if the zinc stops going away, or its rate of deterioration suddenly increases, you have a warning to check things out.

I will try to remember to get the name of the brush manufacturer when we're up at the boat next weekend (if it has a name). I assume it's the same setup as all of them....

This photo is from the BoatElectric webpage and it certainly appears to be identical to what we have. In our case, the two ends of the stainless spring steel strap are held vertically by the spring which is connected under light tension to a fuel tank support by one of those little flat-link chains. The brush is connected to the boat's bonding system by an appropriately sized green wire.

The two curved contacts are curved much sharper than the curve of the 1-1/2" prop shafts, so the points of contact are just the ends of each contact.* And the tension on the spring is not high--- just enough to keep the contacts against the shaft.